Backrest



R. C. ANGELL Dec. Z9

BACKREST Filed Sept. 21 1923 4 Sheets-Sheet 1 i i abe/"f CT Hag/ell,

R. C. ANGELL Dec. 29 1925' BACKREST Filed Sept. 21 1923 4 Sheets-Sheet 2Clttowoq Dec. 29 1925. 1,567,695

R. c. ANGELL BACKREST Filed Sept. 21 1923 4 Sheets-Sheet 5 Dec. 29 1925-1,567,695

R. c. ANGELI.

BACKREST Filed Sept. 21 1923 4 Sheets-Sheet 4 FIC?. .9.

Ffa ja GWW Patented Dec. 29, 1925.

UNITED STATES PATENT OFFICE.

ROBERT c. ANGELI., or rRnron Bannay# YORK. AssIGNoR 'ro THR s. s. WHITEDENTAL MANUFACTURING COMPANY,

A QORPORATION F PENNSYLVNIA.

Vnacmnsr.

Application led September 21, 1923. Serial No. 663,967.

Be it known that l, ROBERT C. ANGEIL, a citizen ot' the United States,and a resident of lrince Bay, in the county of Richmond, State of NewYork, have invented certain new and useful Improvements in Backrests, ofwhich the following is a specification, reference being had to theaccompanying drawings. A

lvly invention relates particularly to thatl type of back-rests that aredesigned for em bodiinent in dental chairs and is vespecially directedtothe conformation of its anterior or supporting surface against whichthe back of an occupant of the chair may rest.

lhc principal objects of my invention are to provide a backrest formedof variably curved transverse zones so related as to afford a concavedanterior surface arranged to closely conform to the back of the humanforni and affording outwardly extending lateral projections tending toclosely embrace the' waist of said form and arranged to afford a feelingof security and consequent comfort and confidence to the occupant of thechair. Y'

Other objects of my invention are to provide a back-rest which may belformed of sheet material shaped to form a shell arranged to coliform tothe back and closely hug the waist of a human form and having itsperimetral margin drawn backwardly to provide a continuous reinforcingflange which may be cooperatively associated with a back plate or shellof sheet material.

My invention comprehends a back-rest that will not only afford maximumcomfort, but that is economical to manufacture, light in weight, readilycovered with leather, fabric, paint, enamel, or other superficialcovering; that will radiate the heat of the body occupying the chair,thereby producing a sensation of coolness in hot weather; and that ishighly sanitary.

My invention further includes novel means for joining the forward andrearward shells of the back-rest together and for hingedly connectingsaid back-rest to its support.

The form of my invention, -as hereinafter described, comprises aback-rest formed of complementary shells of stamped sheet metalrespectively having rim flanges relatively overlapped and joined to forma hollow body whose anterior wall is shaped to conform to the back of ahuman form, and having its upper and lower zones concaved transverselyandits medial zone relatively concaved to conform to the waist of saidform, and affording forwardly extending lateral protuberances tending toclosely tembrace said waist.

My invention also includes all of the various novel features ofconstruction and arrangement as hereinafter more definitely specified.In the accompanying drawings Figure 1 1s a plan view of a back-restconveniently embodying my invention; Fig. 2 is a rear elevational viewof the back-rest shown in Fig. 1; Fig. 3 is a plan View of the forwardshell of said back-rest per se; Fig. 4 is a fr ont elevational view ofsaid forward shell; Fig. 5 1s a central vertical longitudinal sectionalview of the forward shell of said backrest, taken on the axial plane ofsymmetry 5 5; Fig. 6 1s a central vertical longitudinal sectional viewof the assembled backrest, taken on the line 6 6 in Fig. 2; Fig. 7 1s atransverse horizontal sectional view of said back-rest, taken on theline 7 7 in Figs. 2 and 6; Fig. 8 is a transverse sectional view talienin a plane at one-tenth of the length of said back-rest, spaced from thetop on the line 8 8 in Figs. 4 and 5; Fig. 9 is a transverse sectionalview taken in a plane at twotenths of the lengthof said back-rest, onthe line 9 9 in Figs. 4 and 5; Fig. 10 is a transversesectional viewtaken in a plane at threetenths of the length of said back-rest, on theline 10 10 in Figs. 4 and 5; Fig. 11 is a transverse sectional viewtaken in a plane at four-tenths of the length of said hack-rest, on theline 11-11 in Figs. 4 and 5; Fig. 12 is a transverse sectional viewtaken in a plane at five-tenths of the length of. said back-rest, on theline 12 12 in Figs 4 and 5; Fig. 13 is a transverse sectional view takenin a plane at six-tenths of the length of said back-rest, on the line 1313 in Figs. 4 and 5;

' Fig. 14 is a transverse sectional view taken in a plane atseven-tenths of lthe length of said back-rest, on the line 14'-14 inFigs. 4 and 5; Fig. 15 is a transverse sectional view taken in a planeat eight-tenths of the4 length of said back-rest, on the line 15-15 in'Figs. 4 and 5; and Fig. 16 is a transverse sectional view taken in aplane at nine-tenths of the length of said back-rest, spaced'from thetop, on the line 16 16 in Figs. 4 and '5.

In said figures the back-rest comprisesv the forward shell 1 andrearward shell 2, each preferably formed of sheet metal and having rimflanges 3 and 4 relatively telescope'd with their margins preferablyoverlapping to form a hollow body.

Said rearward'shell 2 curves to generally conform to the forward shell 1and has its medial region flattened to afford an inset plane wall 5, towhich the forward shell 1 may be rigidly secured by the transverselyextended strap brackets 6 which as best shown in Fig. 7, have their endssecured to said forward shell by rivets 9 and their rearwardly extendedstraight intermediate portions 11 removably engaged with said plane wall5 of the rearward shell 2 by the screws 12. n'

The rearward shell 2 is also p rovided with reinforcing plates 14 and 15disposed within the shell, to which the back-rest frame 16 may beconveniently attached by the screws 17 and 18 extended through saidshell 2, in threaded engagement with the respective plates 14 and 15.. I

The back-rest frame 16 is provided with recesses 19 affording bearingsfor the trunnions 20 of the rock-shaft 21 upon which the back-rest maybe oscillated to adjust its inclination, and said trunnions aremaintained in said bearings by the retaining plate 22, having theapertures 23 and 24 through 'which the bosses 26 and 27, which affordconvenient attachment to a chair back slide of well known construction,may extend.

The back-rest covering which I have chosen to illustrate, comprises asheet of fabric or leather 30 overlying the metallic shell 1 with aninterposed lining of felt 32, or other suitable resilient material, andhaving its perimetral margin 33 preferably engaged between the opposedtelescoped rim flanges 3 and 4 of the shells 1 and 2, respectively.

rlhe forward shell 1 is shaped to conform to the back of the human form,being concaved transversely and increasing m its curvature from its topand bottom toward its medial transverse zone to conforinto the waist ofsaid human form, and'to provide forwardly projecting lateralprotuberances 36 and 37 of substantial extent, exceeding one-seventh ofthe width of said shell, and tending to closely embrace said waist toafford lateral support for the occupant of the chair.

Said forward shell 1 concavedly curves laterally in opposite directionsfrom the axial plane of symmetry 5 5, and forwardly from a plane 50 50tangent to the transverse curve of said back-rest at the axis ofSymmetry and normal to said plane of symmetry.

In order that the contour of the forward shell 1 of the back-rest may bebetter understood, it has been divided transversely into ten equal partsby horizontal planes 8 8 to 16 16 inclusive, each disposed normal toboth the plane of symmetry 5 5 and the transverse tangential plane50-50, in the order of their numerical notation from the top downward.

As best shown in Figs. 8 to 16 inclusive, representing the transversesections which divide the shell 1 into ten equal parts, the outer marginof said shell is sharply curved backwardly into the rim flange 3, whichthereby affords perimetral convexed ridge crests 34 and 35 variablyspaced both from the plane of symmetry 5 5, and from the transversetangential plane 50-50, and projecting substantially from the latter toits maximum extent between the transverse planes of Sections 13 13 and14--14 to form the lateral protuberances 36 and 37 to which reference ismade.

The crests 34 and 35 of the ridges at the opposite sides of theback-rest are represented by the dash lines on Fig. 4 and are spaced asfollows in the plane of section 8 8, at one-tenth of the length of saidback-rest from the top, said ridge crests are spaced approximately nineand three-quarter inches apart, or sixty-eight-hundredths of the lengthof said back-rest, and approximately one-half inch orthree-and-one-half-hundredths of said length from the tangential plane50 50;`in the plane of section 9 9, at two-tenths of the length of saidback-rest, said crests are spaced approximately twelvevand-oneu rterinches apart or eighty-sixhundredt of the length of the back-rest,

and approximately seven-eights of an inch or six-hundredths of saidlength from the tangential plane 50 50; in the plane of section 10-10,at three-tenths of the length of said back-rest from the top, saidcrests are spaced approximately thirteen-and-one-half inches apart orninety-five-hundrdths of the length of said back-rest, and approximatelyone-and-one-eighth inches or eighthundredths of said length from thetangential plane 50-50; in the plane of section 11 11, at four-tenths ofthe length of said back-rest from the top, said crests are spacedapproximately fourteen and. one eighth inches apart orninety-nine-hundredths of the length of said back-rest, andapproximately one-and-f'ive-eighths inches orelevenand-one-lialf-hundredths of said length from the tangential plane50 50; in the plane of section 12-12, at five-tenths of the length ofsaid back-rest from the top, said crests are spaced approximatelyfourteen-and-one-quarter inches apart or one hundred hundredths of thelength of said back-rest, and approximately two inches or fourteenhundredths of said length from the tangential plane 50 50; in the planeof section 13 13, at six-tenths of the length of said back-rest from thetop, said crests are beck-rest from the top,

spaced approximately fourteen-and-one-half -inches apartor.ninety-eight-hundredths of the length of said back-rest, and.approximately two-and-one-quarter inches oriifteen-and-one-half-hundredths of said length from the tangential plane50'--50; 1n the plane of section 11k-14, at seven-tenths of the lengthof said back-rest from the top, said crests are spaced approximatelythirteen-and-one-quarter inches apart or ninety-three-hundredths of the`length of said .back-rest, and approximately two-andone-quarter inchesor hundredths of said length from the tangential plane 50-'-50; in theplane of section 15-15, at eight-tenths of the length of said saidcrests are spaced approximately twelve-and-.one-half inches apart oreighty'-eight-hundredths of the length of said back-rest, andapproximately one-and-three-quarters inches ortwelve-andone-half-hundredths of said length from the tangential plane50-50; and in theplane of section 16-16, at nine-tenths of the length ofsaid back-rest from the top, said crests are spaced approximatelyelevenand-oneeighth inches apart or seventy-elght-hundredths of thelength of 'said back-rest, and approximately one inch orseven-hundredths of said length from the tangential plane 50-50.

My invention is advantageous in that the proportions herein set forthprovide a backrest that will afford equal comfort tothe back of a widerange of persons of varying size and weight, including alike children aswell as adults.

Although I have described the flanges of the respective shells as beingtelescoped it may be advanta eous in some instances, par- I ticularlywhen t e shells are to be enameled,

to so abut the edges of the flanges as to be welded or otherwise securedand therefore, l do not desire to limit my invention to the precisedetails of construction and ar rangement as herein specified, as it isobvious that various modifications may be made therein without departingfrom the essential features of my invention as defined in the appendedclaims.

Having thus described 'my invention, l claim I 1. A back-rest for adental chair having its longitudinal axis of symmetry dispose in aplane, and its anterior surface variably curved outwardly therefrom andextended laterally forward to form curved protuberances projectingforwardly from said plane approximately one-seventh of the width of saidback-rest and arranged to closely embrace the/waist of a human form.

2. A back-rest for a dental chair havin its longitudinal axis ofsymmetry disposed in a plane, and its anterior surfaces variably curvedoutwardly therefrom and exfteen-and-one-'halfj tended laterally forwardto form curved protuberances projecting forwardly from said plane to anextent exceeding oneseventh of the maximum Width of said backrest andarranged to closely embrace the waist of a human form.

3. A back-rest for a dental chair having its anterior surface curvedoutwardly from a plane tangent to its longitudinal axis of symmetry, andadually increasing in its curvature towar its medial transverse zone toform lateral forwardly extending protuberances projecting from saidplane to an extent approximately one-seventh of the maximum width ofsaid back-rest, and arranged to closely embrace the waist of a humanform.

4. A. back-rest for a dental chair having its anterior surface curvedoutwardly from a plane tangent to its longitudinal axis of symmetry,and'gradually increasing in its curvature from the top and bottom ofsaid back-rest toward its medial transverse zone, and affording lateralforwardly extending protuberances projecting from said plane to thelrmaximum extent at approximately between six-tenths and seven-tenths ofthe length of said back-rest .from the top.

5. iv back-rest for a dental chair having its anterior` surface concavedoutwardly from a plane tangent thereto at its lon itudinal axis ofsymmetry, and gradual y lncreasing in curvature from the top and bottomof said back-rest toward its medial transverse zone, and alordinglateral forwardly extending protuberances projecting from said plane toan extent approximately ifteen-andone-halfhundredths of the length ofsaid back-rest.

6. A back-rest for a dental chair having its anterior surface concaved,curving outwardly from a plane tangent thereto at its longitudinal axisof symmetry and graduall v varying in curvature and turned to form aperimetral convex ridge projecting from said plane approximatelythree-and-onehalf-hundredths of the length vof said backrest atone-tenth of said length from its top; approximately six-hundredths attwotenths; approximately eight-hundredths at three-tenths; approximatelyeleven-and one-half-hundredths at four-tenths; approximatelyfourteen-hundredths at tived tenths; approximately fifteen-andone-halfhundredths at six-tenths; approximately ifteen-and-one-half-hundredthsat seventenths; approximately twelve-and-one-halfhundredths ateight-tenths; and approximately seven-hundredths of the length of saidback-rest at nine-tenths of said length from its to 7 A baci-rest for adental chair having its anterior surface concaved, curving laterallyoutward from a plane tangent to its longitudinal axis of symmetry andnormal to its axial plane of symmetry, and gradually varying incurvature to form a perimetral convex ridge whose crest varies 1nrelation to both said axial plane of symmetry and said tangential plane,being disposed aproximately thirty-four-hundredths of the Fength of saidback-rest from said plane of symmetry and three-and-one-half hundredthsof said length from sald tangential plane, in a transverse plane cuttingsald back-rest at one-tenth of its length from its top;forty-three-hundredths from said plane of symmetry and six-hundredthsfrom said tangential plane, in a transverse plane at two-tenths from thetop; forty-seven-andone-half-hundredths from said plane of symmetry andeight-hundredths from said tangential plane, in a transverse plane, atthree-tenths from the top; forty-nine-andone-half-hundredths from saidplane of symmetry and eleven-and-one-half-hundredths from saidtangential plane, in a transverse plane, at four-tenths from the top;fifty-hundredths from said plane of symmetry and fourteen-hundredthsfrom said tangential plane, in av plane at fivetenths from the top;forty-nine-hundreths from the plane of symmetry andfifteen-ando-ne-half-hundredths from said tangential plane, in a planeat six-tenths from the top;

' fortysix-and-one-halfhundredths f r om said plane of symmetry andfifteen-and-onehalf-hundredths from said tangential plane, in a plane atseven-tenths from the top; forty-four-hundredths from the plane ofsymmetry and twelve-and-one-half-hundredths from said tangential plane,in a plane at eight-tenths from the top, and thirty-nine-hundredths fromthe plane of symmetry and seven-hundredths from said tangential plane,in a plane at nine-tenths of the length of said back-rest from its top.

8. A back-rest for a dental chair having its anterior surface concaved,curving laterally outward from a plane tangent to its longitudinal axisof symmetry, and gradually varying in curvature throughout its extentand affording forwardly directed marginal crests variably spaced bothlaterally and with respect to said tangential plane as follows :-in atransverse plane at one-tenth of the length of said back-rest, theoppositely disposed crests are spaced approximatelynine-and-three-quarters inches apart and approximately one-half inchfrom the tangentlal plane; in a transverse plane at two-tenths of itslength, the opposite crests are spaced twelve-and-one-quarter inchesapart, and seven-eighths of an inch from said tangential plane; in atransverse plane at three-tenths of its length, the opposite crests arespaced thirteen-and-onehalf-inches apart, and one-and-oneeighth theopposite crests are spaced 'fourteen inches apart, andtwoand-one-quarter inches from said tangential plane; in a transverseplane seven-tenths of its length, thc opposite crests are spacedthirteen-andone-quarte'r inches apart, and two-and-onequarter inchesfrom said tangential plane; in a transverse plane eight-tenths of itslength, the opposite crests are spaced twelveand-one-half inches apart,and one-andthree-quarters inches from said tangential plane; and in atransverse plane at ninetenths of its length, the opposite crests arespaced eleven-and-one-eighth inches apart., and one inch from saidtangential plane.

9. A back rest formed of sheet material and comprising a forward shellhaving variably curved transverse zones affording ,laterally disposed,forwardly projecting areas arranged to embrace and closely conform tothe waist of a human form, and havirg its edge margins drawn backwardlyto a ord a reinforcing flange, a rearward shell closely conformin in aspaced relation to said forward s ell, and having a medial inset planewall facilitating attachment of said forward shell therewith, and havinga forwardly drawn flange cooperative with the flange on said forwardshell to form a hollow body; and a strap bracket having its ends Securedto said forward shell and its intermediate portion extended rearwardlyand connected with the plane inset wall of said rearward shell.

l0. A back-rest formed of sheet material and comprising a forward shellhaving its upper and lower zones concaved transversely, and itsintermediate zone relatively curved to conform to the waist of the humanform, and affording forwardly extending lateral protuloerances tendingto closely embrace said waist, a rearward shell closely conforming tosaid forward shell in spaced relation thereto, and having a medial insetplane wallufacilitating attachment to said forward shell, and meansinterposed between said forward and rearward shells arranged to attachthem together.

In witness whereof, I have hereunto set my hand this 31st day of August,A.. D., 1923.

ROBERT e. ANGELL.

